As on the stage systems and networks operation, part of the parameters which are taken into consideration in the design process change its meaning, the project formed earlier can not satisfy the requirements. It is necessary to respect a variability at the time of selected system or network characteristics in the design process. The authors propose a method introducing an indeterminacy to the design process: design criteria, input parameters and model itself. It allows to obtain not one but a

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... t of design solutions which specify given requirements and it is possible to take a human factor into consideration in the solution search process.